Muffle is an effect that reduces both the noise your armor makes when you move and the noise generated by your own footsteps when you move. The "moves silently" description that appears on Muffle items is not entirely accurate; Muffle provides a multiplier equal to (1 - Total_Muffle_Magnitude) to your total worn armor weight when calculating the noise made by armor, meaning at a magnitude of 1.0+ your armor makes no noise whatsoever. All muffle effects stack additively. Values over 1.0 have no additional benefit.[verification needed — see talk page]

The magnitude of the Muffle effect is significant. However, the magnitude of enchantments and spells is not displayed in-game. Most built-in enchanted items have a magnitude of 0.5, meaning they are only 50% effective.

The actual effectiveness of the Muffle effect for magnitudes below 1.0 depends on armor weight, i.e. 50% of the noise of Daedric is still much higher than 100% of the noise of Elven.

All custom-enchanted Muffle effects have a magnitude of 1.0, regardless of skill level or soul gem used, making them greatly superior to most built-in enchanted Muffle items.

Vendors will start carrying Boots of Muffling at level 11.

When both invisible and completely muffled (muffle magnitude of 1.0 or more) you are undetectable to most enemies to the point that you can even walk, run, sprint, and jump around in front of hostile NPCs without being noticed.

Muffle can make players almost undetectable to the Falmer, which rely mostly on hearing to detect enemies.

The probability of finding a disenchantable item with the Muffle effect is extremely low. Because it is a "fixed" effect that does not scale with your level, the probability of finding one is further reduced as you advance in level. This is due to the fact that items with "more valuable" enchantments are given increasingly dominant odds. As a result, if you haven't obtained a Muffle item by level 70, you will probably be unable to obtain one because the probability is so small that it is close to zero. Furthermore, there are no guaranteed locations for disenchantable items of Muffle in the original version of the game. It can only be found via merchants or random loot.

You can use the Atronach Forge to obtain a random enchanted piece of Daedric armor, which has an equal chance of being a pair of Daedric Boots of Muffling as any other Daedric armor. Since it is random, make sure to save before activating the forge if you want to get that specific item. Your chances of getting the boots on any given attempt with this method are about 1%, regardless of your level.

If you're using the exploit of killing vendors and reloading to get them to restock, The Scorched Hammer in Riften is your best bet, since it has more enchanted armor, on average, than any other vendor.